#include<stdio.h>
#include<unistd.h>

#define ONE 0x1     // 0000 0001
#define TWO 0x2     // 0000 0010
#define THREE 0x4   // 0000 0100

void show(int flags){
    if(flags & ONE) printf("hello one\n");
    if(flags & TWO) printf("hello two\n");
    if(flags & THREE) printf("hello three\n");
}

int main(){
    printf("=====================================================\n");
    show(ONE);
    printf("=====================================================\n");
    show(TWO);
    printf("=====================================================\n");
    show(ONE | TWO);
    printf("=====================================================\n");
    show(ONE | TWO | THREE);
    printf("=====================================================\n");
   

    return 0;
}
